Engines may be configured to operate using diesel fuels. There is typically, at least one fuel filter arranged in the fuel system to filter out particles which may be in the diesel fuel. A common issue with diesel fuel filters, in particular at low ambient temperatures, such as during an engine cold-start, is that wax may precipitate out of the diesel fuel. The precipitated wax may clog the fuel filter. The amount of wax that precipitates from the fuel may depend upon the fuel properties and ambient temperature the vehicle is started in. As such, the precipitated wax in the fuel may reduce the pressure of the fuel system, performance of the engine and, if severe enough, can cause damage to the fuel system.
Techniques to mitigate problems associated with precipitated wax clogging diesel fuel filters generally fall into one of two categories. One is to include a heating mechanism with the filter. Another is to recirculate some fuel warmed by the engine through the filter via a recirculation line. Both techniques have shortcomings, but approaches to mitigate diesel fuel filter clogging have mostly been limited to including a heating mechanism with the filter.
One example approach to providing a heating mechanism with the filter is disclosed in US Patent Publication 2003/0116490. The disclosure provides a heater element positioned between an annular outer surface of the filter assembly housing and the fuel filter. Fuel traveling through the fuel filter is heated by the heater element when the fuel temperature is below a predetermined temperature.
The inventors herein have recognized several issues with this approach. For example, the addition of a heating element to the filter may add cost and complexity. Another shortcoming with this approach is, like many similar approaches, it fails to address several shortcomings with the technique of recirculating fuel warmed by the engine back through the filter. The inventors herein have recognized that the warm return fuel from the engine tends to remains near the top of the filter and does not distribute to the lower portion. In effect, the warm fuel does not perform the function it is intended. Embodiments in accordance with the present disclosure address this shortcoming.
Embodiments may provide a fuel filter that may include a plurality of return fuel conduits axially traversing a filter medium. Each conduit may include an inlet in fluidic communication with the fuel recirculation passage. Each conduit may have a return fuel line exit port adjacent to a distal end of the filter medium. In this way, it is possible to provide better thermal management via the fuel filter. For example, by operating via a method that flows heated fuel down the length of the filter through sealed tubes, it is possible to heat a greater amount of the filter to reduce fuel gelling during cold starts, such as with regard to diesel fueled vehicles.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.